Mutilate
Duel Decks Anthology: Garruk vs. Liliana — rare
Sorcery
Mutilate rulings:
2012-07-01: The effect is based on the number of Swamps you control when Mutilate resolves. Only creatures on the battlefield at that time will be affected. The effect won't change later in the turn, even if the number of Swamps you control changes.